Method and apparatus for importing content

ABSTRACT

A method and apparatus for protecting digital content in a digital rights management (DRM) system are provided. The method includes: determining a usage rule for content included in a first content file based on usage constraint information included in the first content file; and generating a second content file complying with this usage rule. According to the method and apparatus, the security requirement of content creators and content providers can be satisfied and at the same time the requirement of content consumers for freer usage can be satisfied.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of application Ser. No. 11/522,437,filed Sep. 18, 2006, which claims the benefit of U.S. Provisional PatentApplication No. 60/755,096, filed on Jan. 3, 2006, in the U.S. Patentand Trademark Office, and Korean Patent Application No. 10-2006-0021838,filed on Mar. 8, 2006, in the Korean Intellectual Property Office, thedisclosures of which are incorporated herein in their entirety byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to digital content protection, and moreparticularly, to protection of digital content in a digital rightsmanagement (DRM) system.

2. Description of the Related Art

As the world is moving from the analogue age to the digital age, morecontent is being created in digitized forms. While copying of analoguecontent requires much time and effort, digital content can be copiedeasily and quickly.

Also, while the quality of the analogue content is degraded inproportion to the frequency of copying, quality of the digital contentis identically maintained regardless of the frequency of copying.Accordingly, protection of digital content has been desired and avariety of research projects for protection of digital content have beenconducted by many companies.

FIG. 1 illustrates a conventional digital content protectionenvironment.

Referring to FIG. 1, in the conventional digital content protectionenvironment, a transmission stream is received through a variety oftransmission channels and digital content is designed to be protected byusing information included in the transmission stream.

In particular, a U.S. organization, Cable Television Laboratories, Inc.(CableLabs), ordered that copy control information (CCI) be attached todigital content in order to control copying of the content. The CCI is2-bit information which restricts the number of times of digital contentmay be copied. The types of CCI includes copy free (00), copy once (01),copy no more (10) and copy never (11). Copy free indicates that copyingthe content is permitted without restriction. Copy once indicates thatonly one copy is permitted. If content with the CCI of copy once (01) iscopied, the CCI of this content then becomes copy no more (10). Copynever indicates a prohibition on copying the content.

In order to prohibit unrestricted redistribution of high definition(HD)-level digital content broadcast in the U.S., the U.S. FederalCommunications Commission (FCC) has ordered that a broadcast flag shouldbe attached to digital content. The broadcast flag is 1-bit informationindicating whether or not unrestricted redistribution of digital contentis prohibited. The types of broadcast flag includes broadcast flag on(1) and broadcast flag off (0). Broadcast flag on indicates thatunrestricted redistribution of digital content is not permitted, whilebroadcast flag off indicates that unrestricted redistribution of thedigital content is permitted.

However, since the conventional methods of protecting digital content,such as the CCI and the broadcast flag, are very simple and limited intheir options, it is difficult to protect digital content while alsosatisfying the needs of content consumers for freer usage of content. Inaddition, with only the conventional methods of the CCI and thebroadcast flag, it is difficult to limit use to authorized users whenthe content is being distributed. Also, these methods are not effectiveto prevent content from being illegally redistributed to or used by manyand unspecified persons.

SUMMARY OF THE INVENTION

The present invention provides an apparatus and method capable ofprotecting digital content while responding to the needs of users forfreer use of the content, allowing only authorized users to use thecontent, and preventing the content from being illegally redistributedto or used by many and unspecified persons.

The present invention also provides a computer readable recording mediumhaving embodied thereon a computer program for executing the method in acomputer system.

According to an aspect of the present invention, there is provided amethod of importing a first content file into a second content file, themethod including: determining a usage rule for content included in thefirst content file based on usage constraint information included in thefirst content file; and generating the second content file complyingwith the determined usage rule.

According to another aspect of the present invention, there is providedan apparatus of importing a first content file into a second contentfile, the apparatus including: a usage rule determination unit whichdetermines a usage rule for content included in the first content filebased on usage constraint information included in the first contentfile; and a content file generation unit which generates a secondcontent file complying with the determined usage rule.

According to still another aspect of the present invention, there isprovided a computer readable recording medium having embodied thereon acomputer program for executing the import method.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings in which:

FIG. 1 illustrates a conventional digital content protectionenvironment;

FIG. 2 illustrates a digital content protection environment according toan embodiment of the present invention;

FIG. 3 illustrates a structure of a content import apparatus accordingto an embodiment of the present invention;

FIG. 4 illustrates a UCI/UR mapping table according to an embodiment ofthe present invention;

FIG. 5 illustrates a format of a license according to an embodiment ofthe present invention; and

FIGS. 6A and 6B are flowcharts illustrating a content import methodaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully with reference tothe accompanying drawings, in which exemplary embodiments of theinvention are shown.

FIG. 2 illustrates a digital content protection environment according toan embodiment of the present invention.

Referring to FIG. 2, the digital content protection environmentaccording to the embodiment of the present invention is composed of avariety of content protection systems, such as a digital rightsmanagement (DRM) system 100, a high bandwidth digital content protection(HDCP) system 200, and a digital transmission content protection (DTCP)system 300, and a plurality of devices 21 through 23 protected by thesecontent protection systems.

The DRM system 100 is a system for managing the rights of contentreceived from the outside. The HDCP system 200 is a system forpreventing copying of digital content output to a digital displaythrough a high bandwidth interface, such as a digital video interface(DVI). The DTCP system 300 is a system for preventing copying of digitalcontent transmitted through a universal serial bus (USB) complying withInstitute of Electrical and Electronics Engineers (IEEE) 1394 standard.In addition to these content protection systems, other contentprotection systems such as a conditional access system (CAS), andcontent protection for recordable media (CPRM) system, may be furtherincluded, which can be easily understood by a person skilled in the artof the present embodiment.

In particular, according to the present embodiment, the DRM system 100includes a content import apparatus 10 which imports digital content,which is protected by the conventional methods of copy control and thebroadcast flag, as digital content complying with a rule of the DRMsystem 100 designed so that the rule can satisfy the securityrequirements of content creators and content providers and at the sametime can satisfy the requirement of content consumers for free usage ofcontent.

The importing of content in the present embodiment is defined as aprocess that a license for content is issued and the content isencrypted according to the rule of the DRM system 100. That is, in thepresent embodiment, the importing of content is a process of convertinga content file not complying with the rule of the DRM system 100 into acontent file complying with the rule of the DRM system 100. In thepresent embodiment, the content file is a file including digitalcontent, and copy control information or a license for the content. Inparticular, a person skilled in the art of the present embodiment willunderstand that the term, ‘a content file’, can also be simply called‘content’.

FIG. 3 illustrates a structure of a content import apparatus accordingto an embodiment of the present invention.

Referring to FIG. 3, the content import apparatus 10 illustrated in FIG.2 is composed of a reception unit 101, a detection unit 102, a usagebind (usage category or scope) determination unit 103, a usage ruledetermination unit 104, a content ID/key generation unit 105, anencryption unit 106, a first encryption unit 1061, a second encryptionunit 1062, a license issuance time measuring unit 107, an electronicsignature unit 108, a license issuance unit 109, a content filegeneration unit 110, a storing unit 111, a storage 112 and atransmission and reception unit 113.

The reception unit 101 receives a transmission stream through a varietyof transmission channels. For example, the reception unit 101 mayreceive a transmission stream through a wireless medium such as asatellite and a ground base station, or through a wired medium such asthe Internet, or through a recording medium such as a digital versatiledisk (DVD).

The detection unit 102 detects any one content file from thetransmission stream received by the reception unit 101, and detects anyone digital content and usage constraint information (UCI) of thiscontent from the content file. The content file detected by thedetection unit 102 does not comply with the rule of the DRM system 100and includes the conventional copy control information or broadcastflag. As illustrated in FIG. 2, the content included in this contentfile may be protected by the DRM system 100 or may be protected by theconventional HDCP system 200 or DTCP system 300. However, in order toprotect the content included in this content file by the DRM system 100,the content file detected by the detection unit 102 should be importedas a content file complying with the rule of the DRM system 100.

Examples of the UCI may include conventional copy control informationand the broadcast flag. As described above, the copy control informationis information which restricts the number of times of copying of digitalcontent. The types of copy control information include copy free, copyonce, copy no more and copy never. Also, the broadcast flag isinformation indicating whether or not unrestricted redistribution of thecontent is prohibited. The types of broadcast flag include broadcastflag on and broadcast flag off.

However, since copy no more is copy control information occurring whendigital content has been copied once, the DRM system 100 cannot receivedigital content with the copy control information of copy no more, andas a result, a case where the DRM system 100 imports content with copyno more cannot occur. This is because the DRM system 100 is a contentprotection system which receives for the first time a transmissionstream through a variety of transmission channels as illustrated in FIG.2, and a case where the DRM system 100 receives content with the copycontrol information of copy no more should not occur. Also, since copynever indicates prohibition of copying content, the DRM system 100cannot copy content with the copy control information of copy never, andas a result, cannot import content with copy never. This is because inorder to import any one digital content, the DRM system 100 should copythe content included in a content file which does not comply with therule of the DRM system 100 and include the copied content in a contentfile which complies with the rule of the DRM system 100.

Also, if the broadcast flag of the content is broadcast flag off,unrestricted redistribution of the content is permitted and protectionof the content by the DRM system 100 is not needed. Accordingly, the DRMsystem 100 does not need to import the content with broadcast flag off.That is, according to the present embodiment, there is no case where thecontent import apparatus 100 imports content with the copy controlinformation of copy no more or copy never, or content with the broadcastflag of broadcast flag off. Accordingly, a case where the copy controlinformation of content is copy no more or copy never, or the broadcastflag of content is broadcast flag off will be excluded in the followingdescription of the present invention.

The usage bind determination unit 103 determines a usage bind of thecontent detected by the detection unit 102 based on the UCI detected bythe detection unit 102 according to the rule of the DRM system 100. A“usage bind” as used herein, essentially corresponds to a defined usagecategory or scope. Considered herein are two categories, the firstwherein usage is confined to a particular device, which will be referredto as a “device bound”, and a second where usage is confined to aparticular domain which may include a variety of devices, which will bereferred to as a “domain bound”. This will now be explained with anexample in which the UCI detected by the detection unit 102 is copycontrol information. That is, if the copy control information detectedby the detection unit 102 is copy free, the usage bind determinationunit 103 determines the usage bind of the content to be a device-bound,which limits the usage of content to any one device, or a domain-boundwhich limits the usage of the content to all devices included in any onedomain. Also, if the copy control information detected by the detectionunit 102 is copy once, the usage bind determination unit 103 determinesthe usage bind of the content to be a device-bound according to the ruleof the DRM system 100.

Since copy free indicates that unrestricted copying of content ispermitted, the usage bind may be either a device-bound or adomain-bound, as described in more detail hereafter.

However, since copy once indicates that only one time copying of thecontent is permitted, the usage bind can only be a device-bound. This isbecause if the usage bind of the content is determined as adomain-bound, free copying of the content among devices included in thedomain should be permitted.

Next, an example in which the UCI detected by the detection unit 102 isthe broadcast flag will now be explained. That is, if the broadcast flagdetected by the detection unit 102 is broadcast flag on, the usage binddetermination unit 103 determines the usage bind of the content to be adevice-bound or a domain-bound according to the rule of the DRM system100. If the broadcast flag is broadcast flag on, this indicates thatunrestricted redistribution of the content is not permitted, thus theusage bind may be a device-bound or a domain-bound. This is because theusage of the content within a device-bound complies with the prohibitionof unrestricted redistribution of the content, and since a domain-boundis a specified area that can be recognized by a user, the usage of thecontent within the domain-bound also complies with the prohibition ofunrestricted redistribution of the content.

Generally, since which domain is composed of which devices is preset bya user, a domain-bound can also be expressed as a user-bound. Also, asdescribed above, since the rule of the DRM system 100 is determined inthe direction that the rule can satisfy the security requirement ofcontent creators and content providers and at the same time can satisfythe requirement of content consumers for free usage of content, theusage bind determination unit 103 determines the usage bind of thecontent as a device-bound or a domain-bound in this direction, i.e., ina balanced manner. Thus device-bound is determined only when determiningthat domain-bound violates the UCI, because the content usage right of auser can be so restricted.

The usage rule determination unit 104 determines a usage rule for thecontent detected by the detection unit 102 based on the UCI detected bythe detection unit 102 according to the rule of the DRM system 100. Morespecifically, the usage rule determination unit 104 determines a usagerule of the content with respect to each usage bind determined by theusage bind determination unit 103. If the usage bind determined by theusage bind determination unit 103 is a device-bound, the usage ruledetermination unit 104 determines a usage rule of the content in any onedevice. If the usage bind determined by the usage bind determinationunit 103 is a domain-bound, the usage rule determination unit 104determines a usage rule of the content in any one domain.

FIG. 4 illustrates a UCI/UR mapping table according to an embodiment ofthe present invention.

Referring to FIG. 4, the UCI/UR mapping table according to theembodiment of the present invention is composed of a UCI field 41, animport field 42, a bind type field 43, and a usage rule field 44.

UCI is recorded in the UCI field 41. In the import field 42, a valueindicating whether or not the content having the UCI recorded in the UCIfield 41 can be imported is recorded. In the bind type field 43, a usagebind based on the UCI recorded in the UCI field is recorded. In theusage rule field 44, a usage rule based on the UCI recorded in the UCIfield with respect to the usage bind recorded in the bind type field 43is recorded.

In particular, among values recorded in the usage rule field 44, ‘all”indicates that all types of usages of content are permitted. Also, amongvalues recorded in the usage rule field 44, “M” indicates moving ofcontent. Moving of the content means that the content stored in any onedevice is deleted the instant the content is stored in another device.Also, among values recorded in the usage rule field 44, “S” indicatesstreaming of content. The streaming of content means that the contentstored in any one device is temporarily output to another device but thecontent is continuously stored in the original device. Also, amongvalues recorded in the usage rule field 44, “P” indicates playing of thecontent. The playing of the content means that any one device plays thecontent.

Since copy free indicates that unrestricted copying of content ispermitted, if the UCI is copy free, “device” and “domain” are recordedin the bind type field 43 and “all” is recorded in the usage rule field44. Meanwhile, since copy once indicates that only one time copying ofcontent is permitted, if the UCI is copy once, device is recorded in thebind type field 43 and “M, S, and P” are recorded in the usage rulefield 44.

In addition to moving, streaming and playing, examples of using contentincludes copying content. The copying of content means that contentimported according to the embodiment of the present invention is copied.However, in order for the content import apparatus 10 to import thecontent, copying of the content is required as a prerequisite and as aresult, if the content imported according to the present embodiment iscopied, the frequency of copying becomes twice.

Accordingly, though the content import apparatus 10 can import contentwith the UCI being copy once, the content import apparatus 10 cannotpermit copying of the content imported according to the presentembodiment. This is the reason why only “M, S, and P” are recorded inthe usage rule field 44 when the UCI is copy once.

Since broadcast flag on indicates that unrestricted redistribution ofcontent is not permitted, if the broadcast flag is broadcast flag on,“device” and “domain” are recorded in the bind type field 43 and “all”is recorded in the usage rule field 44.

Any type of usage in a device-bound, including copying of content,complies with the prohibition of unrestricted redistribution of thecontent, and since a domain-bound is a specified area that can berecognized by a user, any type of usage in the domain-bound, includingcopying of the content, complies with the prohibition of unrestrictedredistribution of the content.

The content ID/key generation unit 105 generates the ID of contentdetected by the detection unit 102 according to the rule of the DRMsystem 100 and generates a content key corresponding to this content ID.The content key generated by the content ID/key generation unit 105 isused to encrypt the content detected in the detection unit 102.

The encryption unit 106 selectively encrypts the content detected by thedetection unit 102 according to the rule of the DRM system 100 based onthe UCI detected by the detection unit 102. That is, if the copy controlinformation is copy no more, or copy never, or the broadcast flag isbroadcast flag off, the content import apparatus 10 does not import thecontent, and therefore the encryption unit 106 does not encrypt thecontent detected by the detection unit 102. The encryption unit 106 iscomposed of the first encryption unit 1061 for encrypting a content keyand the second encryption unit 1062 for encrypting content.

The first encryption unit 1061 encrypts the content key generated by thecontent ID/key generation unit 105 with an encryption key correspondingto a usage bind determined by the usage bind determination unit 103. Ifthe usage bind determined by the usage bind determination unit 103 is adevice-bound, the first encryption unit 1061 encrypts the content keywith an encryption key (hereinafter referred to as a “device key”)corresponding to any one device. If the usage bind determined by theusage bind determination unit 103 is a domain-bound, the firstencryption unit 1061 encrypts the content key with an encryption key(hereinafter referred to as a “domain key”) corresponding to any onedomain.

Accordingly, among devices which receive the content imported by thecontent import apparatus 10, only a device having a device key or domainkey used to encrypt the content keys can decrypt the content keysencrypted by the first encryption unit 1061. Through this encryptionprocess, only users authorized for the content can be selectivelyallowed to use the content and the danger of the content being illegallyredistributed or used by many and unspecified persons can be effectivelyprevented.

For example, in order to allow only a device or domain selected by auser to obtain a content key, the first encryption unit 1061 only needsto encrypt the content key with a device key corresponding to a deviceselected by the user or with a domain key corresponding to a domainselected by the user. However, the first encryption unit 1061 shouldknow which device corresponds to which encryption key, and informationon this relation can be obtained from a server, such as a domainadministrator (not shown).

The second encryption unit 1062 encrypts the content detected by thedetection unit 102 with the content key generated by the content ID/keygeneration unit 105.

If the encryption by the first encryption unit 1061 is finished and thepreparations for issuing a license for the content are complete, thelicense issuance time measuring unit 107 measures a time to issue alicense. By inserting the thus measured license issuance time into thelicense, it can be made that only a device authorized device at the timewhen this license is issued, among devices receiving the contentimported by the content import apparatus 10, can use the content.However, if the license issuance time is faked, the security requirementof content creators and content providers cannot be satisfied and as aresult, the content protection function of the DRM system 100 cannotoperate correctly. Accordingly, a secure time that cannot be manipulatedarbitrarily should be used for the license issuance time.

The electronic signature unit 108 electronically signs the usage ruledetermined by the usage rule determination unit 104 and the licenseissuance time measured by the license issuance time measuring unit 107according to the rule of the DRM system 100. Generally, an electronicsignature is used to guarantee that a document or message is notfalsified. If the usage rule determined by the usage rule determinationunit 104 and the license issuance time measured by the license issuancetime measuring unit 107 are falsified, the security requirement ofcontent creators and content providers cannot be satisfied and as aresult, the content protection function of the DRM system 100 cannotoperate correctly.

The license issuance unit 109 generates and issues a license includingthe content ID generated by the content ID/key generation unit 105, thecontent key encrypted by the first encryption unit 1061, and the usagerule and license issuance time electronically signed by the electronicsignature unit 108. More specifically, the license issuance unit 109generates and issues the license including the usage rule determined bythe usage rule determination unit 104 with respect to the usage binddetermined by the usage bind determination unit 103. If the usage binddetermined by the usage bind determination unit 103 is a device-bound,the license issuance unit 109 generates and issues a license for any onedevice. In particular, in this case, the license issuance unit 109 mayissue a license including license status information to control usage ofthe content by a device which receives the content imported by thecontent import apparatus 10. Here, the license status informationindicates whether or not the content can be used by the device. Thelicense status information is set by the content import apparatus 10 orthe device which receives the content imported by the content importapparatus 10.

If the usage bind determined by the usage bind determination unit 103 isa domain-bound, the license issuance unit 109 generates and issues alicense for any one domain.

FIG. 5 illustrates a format of a license according to an embodiment ofthe present invention.

Referring to FIG. 5, the license according to the present embodiment iscomposed of a content ID 51, an encrypted content key 52, anelectronically signed usage rule and license issuance time 53.

A device which receives the content imported by the content importapparatus 10 can identify the content imported by the content importapparatus 10 by referring to the content ID 51 of the licenseillustrated in FIG. 5. Also, in order to obtain the thus identifiedcontent, the device which receives the content imported by the contentimport apparatus 10 attempts to decrypt the encrypted content key 52 ofthe license illustrated in FIG. 5. As described above, among devicesreceiving the content imported by the content import apparatus 10, onlya device having the device key or domain key used to encrypt the contentkey can decrypt the encrypted content key 52. Also, the device receivingthe content imported by the content import apparatus 10 decrypts thecontent with the key restored through decryption. This is because thecontent imported by the content import apparatus 10 is in an encryptedform as described above.

Also, the device receiving the content imported by the content importapparatus 10 confirms whether or not the electronically signed usagerule and license issuance time 53 of the license illustrated in FIG. 5is falsified and, based on the usage rule and license issuance time 53,confirms whether or not the user is authorized for the content. As aresult, if it is confirmed that the electronically signal usage rule 53is not falsified and the user is authorized for the content, the devicereceiving the content imported by the content import apparatus 10 usesthe content according to the usage rule included in the licenseillustrated in FIG. 5. Accordingly, the security requirement of contentcreators and content providers can be satisfied and at the same time therequirement of content consumers for free usage of the content can besatisfied sufficiently.

The content file generation unit 110 generates a content file complyingwith the usage rule determined by the usage rule determination unit 104according to the rule of the DRM system 100. This is to allow the devicereceiving the content imported by the content import apparatus 10 to usethe content complying with the usage rule determined by the usage ruledetermination unit 104. As described above, the usage rule determined bythe usage rule determination unit 104 is inserted into the licenseissued by the license issuance unit 109. That is, the content filegeneration unit 110 generates a content file including the licenseissued by the license issuance unit 109 and the content encrypted by thesecond encryption unit 1062. However, the license issued by the licenseissuance unit 109 and the content encrypted by the second encryptionunit 1062 may be packaged as one unit or as separate units.

The storing unit 111 stores the content file generated by the contentfile generation unit 110 in the storage 112.

If a request from any one of the devices 21 through 23 illustrated inFIG. 2 to transmit the content to the device is received, thetransmission and reception unit 113 transmits the content file stored inthe storage 112 to this device. The transmission and reception unit 111may transmit the content file according to an arbitrary method that thedevice supports. For example, the content may be transmitted through astorage medium, such as a secure digital (SD) card, or according to atransmission protocol, such as a real-time transport protocol (RTP).

FIGS. 6A and 6B are flowcharts illustrating a content import methodaccording to an embodiment of the present invention.

Referring to FIGS. 6A and 6B, the content import method according to thepresent embodiment is composed of operations processed in time series inthe content import apparatus 10 illustrated in FIG. 3. Accordingly, theexplanation made above in relation to the content import apparatus 10illustrated in FIG. 3, though not repeated below, is also applied to thecontent import method according to the present embodiment.

In operation 601, the content import apparatus 10 receives atransmission stream through a variety of transmission channels.

In operation 602, the content import apparatus 10 detects any onecontent file from the transmission stream received in operation 601, anddetects any one digital content and usage constraint information (UCI)with respect to this content from the content file.

In operation 603, the content import apparatus 10 determines the usagebind of the content detected in operation 602 based on the UCI detectedin operation 602 according to the rule of the DRM system 100.

In operation 604, if the usage bind determined in operation 603 is adevice-bound, the content import apparatus 10 performs operation 605 andif it is a domain-bound, the content import apparatus 10 performsoperation 606.

In operation 605, the content import apparatus 10 determines the usagerule of the content in any one device based on the UCI detected inoperation 602 according to the rule of the DRM system 100.

In operation 606, the content import apparatus 10 determines the usagerule of the content in any one domain based on the UCI detected inoperation 602 according to the rule of the DRM system 100.

In operation 607, the content import apparatus 10 generates the ID ofthe content detected in operation 602 and generates a content keycorresponding to this content ID according to the rule of the DRM system100.

In operation 608, if the usage bind determined in operation 603 is thedevice-bound, the content import apparatus 10 performs operation 609 andif it is the domain-bound, the content import apparatus 10 performsoperation 610.

In operation 609, the content import apparatus 10 encrypts the contentkey with a device key corresponding to any one device according to therule of the DRM system 100.

In operation 610, the content import apparatus 10 encrypts the contentkey with a domain key corresponding to any one domain according to therule of the DRM system 100.

In operation 611, the content import apparatus 10 encrypts the contentdetected in operation 602 with the content key generated in operation607 based on the UCI detected in operation 602.

In operation 612, if the encryption in operation 609 or 610 is finishedand preparation for issuing a license is finished, the content importapparatus 10 measures the time to issue a license.

In operation 613, the content import apparatus 10 electronically signsthe usage rule determined in operation 605 or 606 and the licenseissuance time measured in operation 612 according to the rule of the DRMsystem 100.

In operation 614, according to the rule of the DRM system 100 thecontent import apparatus 10 generates and issues a license including thecontent ID generated in operation 607, the content key encrypted inoperation 609 or 610, and the usage rule and license issuance timeelectronically signed in operation 613.

In operation 615, the content import apparatus 10 generates a contentfile complying with the usage rule determined in operation 605 or 606according to the rule of the DRM system 100. That is, in operation 615,the content import apparatus 10 generates the content file including thelicense issued in operation 614 and the content encrypted in operation611.

In operation 616, the content import apparatus 10 stores the contentfile generated in operation 615.

In operation 617, if a request from any one of the devices 21 through 23illustrated in FIG. 2 to transmit the content to the device is received,the content import apparatus 10 performs operation 618.

In operation 618, the content import apparatus 10 transmits the contentfile stored in operation 616.

The present invention can also be embodied as computer readable codes ona computer readable recording medium. The computer readable recordingmedium is any data storage device that can store data which can bethereafter read by a computer system. Examples of the computer readablerecording medium include read-only memory (ROM), random-access memory(RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storagedevices, and carrier waves (such as data transmission through theInternet).

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims. Thepreferred embodiments should be considered in descriptive sense only andnot for purposes of limitation. Therefore, the scope of the invention isdefined not by the detailed description of the invention but by theappended claims, and all differences within the scope of the claims willbe construed as being included in the present invention.

According to the present invention, content which does not comply withthe rule of a DRM system is imported as content complying with the ruleof the DRM system. By doing so, the content can be protected while beingresponsive to the demand of users for free usage, and only usersauthorized for the content can be allowed to use the content. As aresult, the danger of content being illegally redistributed or used bymany and unspecified persons can be prevented.

In particular, according to the present invention, based on usageconstraint information included in a content file received from theoutside, for example, the copy control information and the broadcastflag, the usage rule of the content included in this content file isdetermined and a content file complying with this usage rule isgenerated. By doing so, in addition to the limited content protection bythe conventional copying control and broadcast flag, the securityrequirement of content creators and content providers can be satisfiedand at the same time the requirement of content consumers for free usagecan be satisfied sufficiently.

1. A method of importing a first content file into a second contentfile, the method comprising: receiving at a computer implementing adigital rights management (DRM) system a first content file which doesnot comply with a DRM usage rule for the DRM system and which includesusage constraint information; determining the DRM usage rule for contentincluded in the first content file based on the usage constraintinformation included in the first content file; generating the secondcontent file complying with the determined DRM usage rule; andgenerating and issuing a license of the content including the determinedDRM usage rule, wherein in the generating of the second content file,the second content file including the issued license is generated, andwherein the second content file includes the determined DRM usage rule.2. The method of claim 1, wherein the information is usage constraintinformation of the content and in the determining of the DRM usage rulethe DRM usage rule is determined based on the usage constraintinformation.
 3. The method of claim 2, wherein the usage constraintinformation is information restricting the number of times of copyingthe content.
 4. The method of claim 2, wherein the usage constraintinformation is information indicating whether or not unrestrictedredistribution of the content is prohibited.
 5. The method of claim 1,further comprising encrypting selectively the content based on theinformation, wherein in the generation of the second content file, thesecond content file including the DRM usage rule and the encryptedcontent is generated.
 6. The method of claim 1, further comprisingdetermining the usage bind of the content based on the information,wherein in the determining of the DRM usage rule, the DRM usage rule isdetermined with respect to each determined usage bind.
 7. The method ofclaim 1, further comprising measuring the time to issue the license,wherein in the generating and issuing of the license of the content, thelicense further including the measured time is generated and issued. 8.The method of claim 1, further comprising: electronically signing thedetermined DRM usage rule; and generating and issuing a license of thecontent including the electronically signed usage rule.
 9. The method ofclaim 1, wherein the first content file does not comply with the DRMrule of a DRM system and the second content file complies with the DRMrule of the DRM system.
 10. An apparatus for importing a first contentfile as a second content file, the apparatus comprising: a receptiondevice which receives the first content file which does not comply witha digital rights management (DRM) usage rule for a DRM system; a usagerule determination device which determines the DRM usage rule forcontent included in the first content file based on usage constraintinformation included in the first content file; a content filegeneration device which generates the second content file complying withthe determined DRM usage rule; and a license issuance unit generatingand issuing a license of the content including the determined DRM usagerule, wherein the content file generation device generates the secondcontent file including the issued license, and wherein the secondcontent file includes the determined DRM usage rule.
 11. The apparatusof claim 10, wherein the information is usage constraint information ofthe content and the usage rule determination device determines the DRMusage rule based on the usage constraint information.
 12. The apparatusof claim 10, further comprising a usage bind determination devicedetermining the usage bind of the content based on the information,wherein the usage rule determination device determines the DRM usagerule with respect to each determined usage bind.
 13. A non-transitorycomputer readable recording medium having embodied thereon a computerprogram that when executed by a computer causes the computer to executea method of importing a first content file into a second content file,wherein the method comprises: receiving at a computer implementing adigital rights management (DRM) system a first content file which doesnot comply with a digital rights management (DRM) usage rule for the DRMsystem and which includes usage constraint information; determining theDRM usage rule for content included in the first content file based onthe usage constraint information included in the first content file;generating the second content file complying with the determined DRMusage rule; and generating and issuing a license of the contentincluding the determined DRM usage rule, wherein in the generating ofthe second content file, the second content file including the issuedlicense is generated, and wherein the second content file includes thedetermined DRM usage rule.